using System; using System.Collections; using System.Collections.Generic; using System.Collections.Specialized; using System.Text; namespace Apewer { /// <summary>集合的实用工具。</summary> public static class CollectionUtility { #region 判断 /// <summary>判断集合为空。</summary> public static bool IsEmpty<T>(IEnumerable<T> objects) { if (objects == null) return true; if (objects is T[]) return ((T[])objects).LongLength < 1L; if (objects is ICollection<T>) return ((ICollection<T>)objects).Count < 1; foreach (var item in objects) return false; return true; } /// <summary>判断集合存在元素。</summary> public static bool NotEmpty<T>(IEnumerable<T> objects) { if (objects == null) return false; if (objects is T[]) return ((T[])objects).LongLength > 0L; if (objects is ICollection<T>) return ((ICollection<T>)objects).Count > 0; foreach (var item in objects) return true; return false; } /// <summary>获取集合中元素的数量。</summary> public static int Count<T>(IEnumerable<T> objects) { if (objects == null) return 0; var array = objects as T[]; if (array != null) return array.Length; var collection = objects as ICollection<T>; if (collection != null) return collection.Count; var count = 0; foreach (var cell in objects) count++; return count; } /// <summary>检查集合是否包含 item。</summary> public static bool Contains<T>(IEnumerable<T> objects, T cell) { if (objects == null) return false; // objects 实现了含有 Contains 方法的接口。 if (objects is ICollection<T>) return ((ICollection<T>)objects).Contains(cell); // cell 无效。 if (cell == null) { foreach (var i in objects) { if (i == null) return true; } return false; } // cell 有效,进行默认比较。 var comparer = EqualityComparer<T>.Default; foreach (var i in objects) { if (comparer.Equals(i, cell)) return true; } return false; } /// <summary>获取 item 在集合中的偏移位置,不存在时返回 -1。</summary> public static int IndexOf<T>(IEnumerable<T> objects, T item) { if (objects == null) return -1; if (objects is IList list) return list.IndexOf(item); if (item == null) { if (objects is T[] array) { var length = array.Length; for (var i = 0; i < length; i++) { if (array[i] == null) return i; } return -1; } var index = 0; foreach (var obj in objects) { if (obj == null) return index; index++; } return -1; } else { var comparer = EqualityComparer<T>.Default; if (objects is T[] array) { var length = array.Length; for (var i = 0; i < length; i++) { if (comparer.Equals(item, array[i])) return i; } return -1; } var index = 0; foreach (var obj in objects) { if (comparer.Equals(item, obj)) return index; index++; } return -1; } } #endregion #region 类型转换 /// <summary>转换模型类型。</summary> public static TDst[] As<TSrc, TDst>(this TSrc[] array) where TDst : class { if (array == null) return null; var count = array.Length; var output = new TDst[count]; for (var i = 0; i < count; i++) { var item = array[i]; if (item == null) continue; output[i] = item as TDst; } return output; } /// <summary>转换模型类型。</summary> public static TDst[] As<TSrc, TDst>(this TSrc[] array, Func<TSrc, TDst> convert) { if (convert == null) throw new ArgumentNullException(nameof(convert)); if (array == null) return null; var count = array.Length; var output = new TDst[count]; for (var i = 0; i < count; i++) { var item = array[i]; if (item == null) continue; output[i] = convert(item); } return output; } /// <summary>安全转换为 List<<typeparamref name="T"/>> 对象。可指定排除 NULL 值元素。</summary> public static List<T> List<T>(IEnumerable<T> objects, bool excludeNull = false) { if (objects == null) return new List<T>(); var list = new List<T>(); var collection = objects as ICollection; if (collection != null) { list.AddRange(objects); } else { var group = 1024; var added = 0; var capacity = 0; if (objects != null) { foreach (var item in objects) { if (excludeNull && item == null) continue; if (added == capacity) { capacity += group; list.Capacity = capacity; } list.Add(item); added += 1; } } list.Capacity = added; } return list; } /// <summary>安全转换为 <<typeparamref name="T"/>>[] 对象。可指定排除 NULL 值元素。</summary> public static T[] Array<T>(IEnumerable<T> objects, bool excludeNull = false) { if (objects == null) return new T[0]; if (objects is T[]) return (T[])objects; var collection = objects as ICollection; if (collection != null) { var array = new T[collection.Count]; collection.CopyTo(array, 0); return array; } else { var group = 1024; var array = new T[group]; var added = 0; var capacity = 0; foreach (var item in objects) { if (excludeNull && item == null) continue; if (added == capacity) { capacity += group; var temp = new T[capacity]; System.Array.Copy(array, 0, temp, 0, added); array = temp; } array[added] = item; added += 1; } if (added < 1 || added == capacity) return array; var collapsed = new T[added]; System.Array.Copy(array, 0, collapsed, 0, added); return collapsed; } } /// <summary>生成 StringPairs 对象实例为副本。</summary> public static StringPairs StringPairs(NameValueCollection @this) => Apewer.StringPairs.From(@this); /// <summary>转换集合为数组。</summary> /// <param name="collection"></param> /// <returns></returns> public static Dictionary<string, string[]> Dictionary(NameValueCollection collection) { if (collection == null) return null; var count = collection.Count; var dict = new Dictionary<string, string[]>(); for (var i = 0; i < count; i++) { var key = collection.GetKey(i); var values = collection.GetValues(i); dict.Add(key, values); } return dict; } /// <summary>转换集合为字典。</summary> /// <typeparam name="TKey">字典 Key 的类型。</typeparam> /// <typeparam name="TValue">字典 Value 的类型。</typeparam> /// <param name="items">要转换的集合。</param> /// <param name="key">根据元素获取 Key 的函数。</param> /// <exception cref="ArgumentNullException"></exception> public static Dictionary<TKey, TValue> Dictionary<TKey, TValue>(IEnumerable<TValue> items, Func<TValue, TKey> key) { if (items == null) throw new ArgumentNullException(nameof(items)); if (key == null) throw new ArgumentNullException(nameof(key)); var dict = new Dictionary<TKey, TValue>(); foreach (var i in items) { if (i == null) continue; var k = key(i); if (k.IsNull()) continue; if (dict.ContainsKey(k)) continue; dict.Add(k, i); } return dict; } #endregion #region 修改集合 /// <summary>添加多个元素。</summary> public static void Add<T>(List<T> list, params T[] items) { if (list != null && items != null) list.AddRange(items); } /// <summary>添加多个元素。</summary> public static IList<T> Add<T>(IList<T> list, IEnumerable<T> items) { if (list != null && items != null) { foreach (var item in items) list.Add(item); } return list; } /// <summary>添加元素。</summary> public static bool Add<TKey, TValue>(IList<KeyValuePair<TKey, TValue>> list, TKey key, TValue value) { if (list == null) return false; list.Add(new KeyValuePair<TKey, TValue>(key, value)); return true; } /// <summary>对元素去重,且去除 NULL 值。</summary> public static T[] Distinct<T>(IEnumerable<T> items) { if (items == null) throw new ArgumentNullException(nameof(items)); var count = Count(items); var added = 0; var array = new T[count]; var comparer = EqualityComparer<T>.Default; foreach (var item in items) { if (item == null) continue; var contains = false; foreach (var i in array) { if (comparer.Equals(i, item)) { contains = true; break; } } if (contains) continue; array[added] = item; added++; } if (added < count) { var temp = new T[added]; System.Array.Copy(array, 0, temp, 0, added); array = temp; } return array; } /// <summary>获取可枚举集合的部分元素。</summary> /// <typeparam name="T">集合元素的类型。</typeparam> /// <param name="objects">原集合。</param> /// <param name="skip">在集合前段要跳过的元素数量。</param> /// <param name="count">要获取的元素数量,指定为负数时不限元素数量。</param> /// <param name="stuffer">填充器,获取范围超出原集合的部分,使用此方法填充元素;此函数默认返回 <typeparamref name="T"/> 的默认值。</param> /// <returns>数量符合 count 的数组。</returns> public static T[] Slice<T>(IEnumerable<T> objects, int skip = 0, int count = -1, Func<T> stuffer = null) { if (count == 0) return new T[0]; var ab = new ArrayBuilder<T>(); var added = 0; if (skip < 0) { var end = 0 - skip; for (var i = 0; i < end; i++) { ab.Add(stuffer == null ? default : stuffer()); added++; if (count > 0 && added == count) return ab.Export(); } } if (objects != null) { var offset = 0; foreach (var item in objects) { if (offset < skip) { offset++; continue; } ab.Add(item); added++; offset++; if (count > 0 && added == count) return ab.Export(); } } while (added < count) { ab.Add(stuffer == null ? default : stuffer()); added++; } return ab.Export(); } #endregion #region 排序 /// <summary>对列表中的元素排序。</summary> public static List<T> Sort<T>(List<T> list, Func<T, T, int> comparison) { if (list == null) return null; if (comparison == null) return list; list.Sort(new Comparison<T>(comparison)); return list; } /// <summary>对数组排序。</summary> /// <exception cref="NullReferenceException"></exception> public static T[] Sort<T>(T[] array, Func<T, T, int> comparison) { if (array == null) return array; if (comparison == null) return array; System.Array.Sort(array, new Comparison<T>(comparison)); return array; } /// <summary>获取集合中的第一个元素。可指定失败时的默认返回值。</summary> public static T First<T>(IEnumerable<T> collection, T failed = default(T)) { if (collection == null) return failed; var array = collection as T[]; if (array != null) return array.Length > 0 ? array[0] : failed; var list = collection as IList<T>; if (list != null) return list.Count > 0 ? list[0] : failed; foreach (var item in collection) return item; return failed; } /// <summary>获取集合中的最后一个元素。可指定失败时的默认返回值。</summary> public static T Last<T>(IEnumerable<T> collection, T failed = default(T)) { if (collection == null) return failed; var array = collection as T[]; if (array != null) return array.Length > 0 ? array[array.Length - 1] : failed; var list = collection as IList<T>; if (list != null) return list.Count > 0 ? list[list.Count - 1] : failed; var value = failed; foreach (var item in collection) value = item; return value; } /// <summary>对数组升序排序。</summary> /// <exception cref="NullReferenceException"></exception> public static T[] Ascend<T>(T[] array) where T : IComparable<T> { if (array == null) return null; array.Sort((a, b) => a.CompareTo(b)); return array; } /// <summary>对数组升序排序。</summary> /// <exception cref="NullReferenceException"></exception> public static List<T> Ascend<T>(List<T> list) where T : IComparable<T> { if (list == null) return null; list.Sort((a, b) => a.CompareTo(b)); return list; } /// <summary>对数组升序排序。</summary> /// <exception cref="NullReferenceException"></exception> public static void Ascend<T, TProp>(T[] array, Func<T, TProp> func) where TProp : IComparable<TProp> { if (array != null && func != null) Sort(array, (a, b) => func(a).CompareTo(func(b))); } /// <summary>对数组降序排序。</summary> /// <exception cref="NullReferenceException"></exception> public static T[] Descend<T>(T[] array) where T : IComparable<T> { if (array == null) return array; Sort(array, (a, b) => 0 - a.CompareTo(b)); return array; } /// <summary>对数组降序排序。</summary> /// <exception cref="NullReferenceException"></exception> public static List<T> Descend<T>(List<T> list) where T : IComparable<T> { if (list == null) return null; list.Sort((a, b) => -a.CompareTo(b)); return list; } /// <summary>对数组降序排序。</summary> /// <exception cref="NullReferenceException"></exception> public static void Descend<T, TProp>(T[] array, Func<T, TProp> func) where TProp : IComparable<TProp> { if (array != null && func != null) Sort(array, (a, b) => 0 - func(a).CompareTo(func(b))); } /// <summary>对字典中的键排序。</summary> public static Dictionary<TKey, TValue> SortKey<TKey, TValue>(Dictionary<TKey, TValue> dict, Func<TKey, TKey, int> comparison) { if (dict == null) return null; if (comparison == null) return null; var list = new List<KeyValuePair<TKey, TValue>>(dict); list.Sort(new Comparison<KeyValuePair<TKey, TValue>>((a, b) => comparison(a.Key, b.Key))); dict.Clear(); foreach (var item in list) dict.Add(item.Key, item.Value); return dict; } /// <summary>对字典中的键排序。</summary> public static Dictionary<TKey, TValue> SortKey<TKey, TValue>(Dictionary<TKey, TValue> @this) where TKey : IComparable<TKey> { return SortKey(@this, (a, b) => a.CompareTo(b)); } /// <summary>对字典中的值排序。</summary> public static Dictionary<TKey, TValue> SortValue<TKey, TValue>(Dictionary<TKey, TValue> dict, Func<TValue, TValue, int> comparison) { if (dict == null) return null; if (comparison == null) return dict; var list = new List<KeyValuePair<TKey, TValue>>(dict); list.Sort(new Comparison<KeyValuePair<TKey, TValue>>((a, b) => comparison(a.Value, b.Value))); dict.Clear(); foreach (var item in list) dict.Add(item.Key, item.Value); return dict; } /// <summary>对字典中的值排序。</summary> public static Dictionary<TKey, TValue> SortValue<TKey, TValue>(Dictionary<TKey, TValue> @this) where TValue : IComparable<TValue> { return SortValue(@this, (a, b) => a.CompareTo(b)); } #endregion #region params internal static object[] ParseParams(object cells) { var parsed = new ArrayBuilder<object>(); ParseParams(cells, parsed, 1); return parsed; } static void ParseParams(object cells, ArrayBuilder<object> parsed, int depth) { if (cells.IsNull()) return; if (cells is string str) { parsed.Add(cells); return; } if (cells is IList items) { if (depth > 64) { parsed.Add(nameof(IList)); return; } var count = items.Count; for (var i = 0; i < count; i++) { ParseParams(items[i], parsed, depth + 1); } return; } parsed.Add(cells.ToString()); } #endregion } }